The present disclosure relates generally to brushless synchronous machines with a DC power supply incorporated with the rotor. In conventional brushless synchronous machines, a DC power supply provides an excitation current to a rotor field winding, the excitation current having characteristics controllable by an external exciter unit, an external automatic voltage regulator, or a DC current regulator within the DC power supply, to name but a few examples. Existing DC power supplies suffer from a number of shortcomings and disadvantages. There remain unmet needs such as reducing machine noise or vibration, increasing machine responsiveness to fault events or shut down events, reducing DC power supply complexity, and increasing DC power supply reliability. For instance, delayed field winding de-excitation during faults or shut down events increase the risk of damage to synchronous machine components such as the DC power supply. There is a significant need for the unique apparatuses, methods, systems and techniques disclosed herein.